download the latest FreeNAS 64 bit disk image and extract it using 7zip

use Win32DiskImager to copy the extracted FreeNAS image onto a new jump drive (minimum size 4Gb)

I used a spare Lexar Firefly jump drive that I had lying around because it is small and easy to insert into the usb port on the Microserver motherboard.

When I logged into FreeNAS again I had to change the admin password. I then uploaded my previous saved configuration and rebooted.

Always take a couple of minutes to save your FreeNAS config (you never know when you might need it).

With this done I just had to deal with the warning that my zpools were using an older version of ZFS (15) than was currently running (28). Time to enable SSH so that we can do a little command line work and upgrade my zpools.

Select Control Services under Services in the left hand pane and then enable SSH. Then click the spanner icon to open the SSH Settings window and check Login as Root with password and click OK.

Next open Putty (or a similar tool) and remote into FreeNAS as root (using your Admin password).

I used the following commands to upgrade my zpools:

Note: it is recommended to back-up your data before performing an upgrade and it is not recommended to upgrade zpools if they are not healthy.

zpool status
zpool upgrade <pool-name>

With the pool upgrade complete I made sure that I turned off SSH access.

Now that all of that is out of the way my file transfers are back to normal again. I still want to investigate the dips that I experience during file transfers, but the impact is not so great that it is a really pressing concern.

My main take-away from this is to make sure that I keep my config backed-up and always have a spare jump drive to replace a failed one. It happened to me much sooner than I thought it would!